Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 8,895	$ 29,988
Prepaid expenses and other current assets	11,302	3,018
Total current assets	20,197	33,006
Property and equipment, net	1,048	1,173
Operating lease assets	364	455
Other assets	123	123
Total assets	21,732	34,757
Current liabilities:
Accounts payable	3,082	1,030
Loan payable, net of discount	4,893	9,852
Accrued expenses and other current liabilities	1,687	4,480
Operating lease liabilities, net of discount	454	317
Total current liabilities	10,116	15,679
Operating lease liabilities, net of current portion and discount		210
Total liabilities	10,116	15,889
Commitments and contingencies (Note 6)
Stockholders’ equity:
Undesignated preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.001 par value; 200,000,000 shares authorized; 89,774,309 and 82,969,421 shares issued and outstanding at March 31, 2022 and December 31, 2021, respectively	90	83
Additional paid-in capital	269,791	265,237
Accumulated deficit	(258,265)	(246,452)
Total stockholders’ equity	11,616	18,868
Total liabilities and stockholders’ equity	$ 21,732	$ 34,757